Sheetsxsheet i



April 1, 1952 D. w. RAU 2,591,197

FLUID PRESSURE REGULATING APPARATUS Filed Dec. 20, 1947 2 SHEETS-SHEET 1 WITNESS: INVEN'IOR Dav/D W Pm) ATTORNEY April 1, 1952 D. w. RAU 2,

FLUID PRESSURE REGULATING APPARATUS Filed Dec. 20, 194'? 2 SHEETSSHEET 2 I/VITNESS: IM'ENTOR DA w W flaw RY M Patented Apr. 1, 1952 FLUID PRESSURE REGULATING APPARATUS David W. Ran, Kirkwood, Mo., assignor to Vickers, Incorporated, a corporation of Michigan Application December 29, 1947, Serial No. 792,938

This invention relates to improvements in regulating apparatus. More particularly this invention relates to improvements in regulating apparatus which can set and maintain a desired pressure on a given quantity of gas.

It is therefore an object of the present invention to provide an improved regulating device which can be used to set and maintain a desired pressure on a given quantity of gas.

In working with gases for various purposes, it would be desirable to be able to treat the gases as though they were always subjected to a predetermined and fixed ambient pressure. However, as is well known, the ambient or atmospheric pressure is not fixed; instead that pressure varies considerably from time to time. As a result, in the absence of regulating apparatus that can set and maintain a constant pressure for confined gas, a person doing work with gases based upon the volume of those gases will find it necessary to make frequent tests of the barometric pressure and then correct the observed volume measurements of the gas.

measurements, and of making calculations and corrections based upon those measurements, in-

troducing considerable probability of human er- For these reasons, work done with gases based upon the volume of those gases is slow and islikely to be in error. This is objeotionable. The present invention obviates these objections by providing a regulating device which operates, despite'variations'in ambient. pressure,

to maintain a fixed and constant pressure on a given quantity of gas. It is therefore an object of the present invention to provide a regulating device which operates, despite variations in ambient pressure, to maintain a fixed and constant pressure on a given quantity of gas.

It is oftentimes desirable, when working with gases, to create a fixed pressure, greater than the ambient pressure, and to maintain that fixed pressure on those gases for considerable periods of time irrespective of variations in the ambient pressure. Where this is done, numerous calculations and visual observations, with their attendant human errors, can be obviated.

The present invention makes it possible to set and maintain a fixed pressure, greater than the ambient pressure, by providing a liquid column that moves in response to variations in ambient pressure and by providing a bubbler tube that extends down into the liquid column. With this 20 Claims. (01. 137-53) arrangement, the instantaneous total or absolute pressure on the gas in the bubbler tube will be the sum of the instantaneous ambient pressure and the instantaneous hydrostatic pressure on the liquid at the bottom of the bubbler tube. Moreover, the total instantaneous pressure can be made to remain unchanged despite variations in ambient pressure, since the regulating device can be dimensioned so a change in instantaneous ambient pressure is always accompanied by 'an equal but opposite change in hydrostatic pressure. Thus, while the instantaneous ambient and hydrostatic pressures may change frequently, the instantaneous total pressure in the bubbler tube will always remain the same. By placing gases in a container and by connecting that container to the bubbler tube, it is possibleto maintain a pressure on the gases in that container which will remain unchanged despite variations in ambient pressure. It is therefore an object of the present invention to connect a container to a bubbler tube which extends dowm into a liquid column that moves in response to variations in ambient pressure.

In making selenium rectifiers it isirequently desirable to chemically modify the selenium. This practice is known as inoculating selenium; and in inoculating selenium it is oftentimes desirable to measure out a predetermined quantity of gas, and then to move that gas into contact with the selenium. To obtain a uniform amount of inoculation each time, the volume of the gaseousinoculant should be measured at the same pressure a-nd'temperature each time. By using the regulating device of the present invention it is possible to obtain the exact amount of inoculant each and every time, irrespective of variations in ambient pressure. It is therefore an object of the present invention to provide a regulating device which Will draw in a predetermined quantity of gaseous inoculant, measure the volume of that inoculant at a fixed pressure, and then force the inoculant into contact with selenium.

Other and further objects and advantages of the present invention should become apparent from an examination of the drawing and accompanying description.

In the drawing and accompanying description on a preferred embodiment of the present invention is shown and described but it is to be understood that the drawing and accompanying description are for the purposes of illustration only and do not limit'the invention and that the invention will be defined by the appended claims.

In the drawing, Fig. 1 is a side elevational view of a. regulating device that is made in accordance with the principles and teachings of the present invention,

, Fig. 2 is a side elevational view of the regulating device of Fig. 1 as it is used with an open manometer,

Fig. 3 is a side elevational view of the regulat ing device of Fig. 1 as it is used with a gas measuring device, and

Fig. 4 is a side elevational view of the regulating device of Fig. l as it is used with distillation apparatus.

Referring to the drawing in detail, the numeral I denotes an enlarged bulb which has a closed top and closed sides but has an opening in the bottom thereof. A U-tube I2 has one of its ends sealed to the opening in the bottom of the bulb Ill, and it has an enlarged reservoir id at its other end. The reservoir I d is vertically disposed and the upper end thereof receives and supports a spray trap E6 in an air-tight seal. Where the regulating apparatus is made of glass, the spray trap k6 is preferably fused to the top or" the reservoir I 3. Where the regulating apparatus is made of metal or other materials, the spray trap I6 can be sealed to the reservoir It by means of gaskets, welding, or the like. The spray trap It has circular openings at the top and bottom thereof, and those openings are large enough to accommodate a bubbler or pressure relief tube 26. The diameter of the bubbler tube 26 is small enough to permit air or gas to pass through the space between the outer periphery of the tube 2% and the inner periphery of the opening at the bottom of the spray trap I6, but that diameter is large enough so the tube 29 can be guided and supported by the spray trap I5.

Air or gas passing upwardly along the sides of the bubbler tube 28 will pass through the bottom opening in the spray trap I6 and through the outlet it! of spray trap It to the surrounding atmosphere. However, fluid that tends to form bubbles or spray and tends to move upwardly with that gas or air will, in most instances, be stopped by reservoir I4. The upper end of the bubbler tube 5 2|] extends upwardly beyond the upper end of spray trap l6 and it is provided with an inlet 22. This inlet may be connected to any suitable source of air or gas under pressure. Air or gas introduced into the inlet 22 will pass downwardly to the lower end of bubbler tube 2!! and issue into the fluid 26 within the reservoir It. The fluid 26 of reservoir l4 occupies the entire volume of the U-tube I2 and approximately one half of the enlarged bulb Hi. The level of the fluid in bulb I0 is preferably set so it is at that portion of bulb I!) which has the largest internal area. The rest of bulb H) is evacuated; and the difference between the vacuum in bulb Ill and the pressure of the atmosphere surrounding outlet N3 of spray trap IE will determine'the heights of the fluid 26 in bulb I0 and reservoir I4. A resilient sleeve 24 closely surrounds the bubbler tube and the upper end 9f the spray trap l6; and this sleeve permits adjustment of the vertical position of bubbler tube 20 relative to spray trap 29 whilesealin tube 20 to trap It. With this arrangement, air or gas introduced into inlet 22 must pass through the fluid 26 which is above the lower end of bubbler tube 20 and must pass to the outlet I8 of spray trap I 6.

The fluid 26 which is confined within the bulb Ifl, U-tube I2, and reservoir I4 is preferably a dense liquid such as mercury. That fluid can be introduced into the bulb I 0, U-tube I2, and reservoir I4 in such a way that the bulb I0 and U- tube H are initially completely filled with fluid and are thus completely devoid of air and gas. Thereafter the bulb l0, U--tube I2 and reservoir M can be made to assume the position shown in Fig. l, whereupon the fluid 26 will move downwardly in bulb Ill andgU-tube I2 until the pressure of the atmosphere surrounding outlet I8 of spray trap I6 is sufllcient to resist further downward movement of that fluid. The exact level of the fluid 26 in bulb I0 and reservoir I4 will never be fixed since it will vary whenever the pressure of the atmosphere surrounding outlet I8 of spray trap I6 varies. The principal variation in the level of fluid 26 Will occur in reservoir I4, and only very minor variations will occur in the level of the fluid in bulb l0; since the diameter of bulb I0 is much larger than the diameterof reservoir I4. By making the diameter of the bulb I0 approximately ten (10) times as large as the diameter of reservoir I4, it is possible to have the level in reservoir I4 move one hundred (100) times the distance moved by the level in bulb II]. As a result, the

fluid level in reservoir I4 is quite responsive to I tube 20 will be subject to two separate pressures;

one being ambient pressure, and the other being hydrostatic pressure due to the fluid 26 above the lower end of bubbler tube 20. The two pressures combine to provide a total absolute pressure on the air or gas. will change from time to time; and since the hydrostatic pressure is determined by the relative heights of the fluid 26 in bulb I0 and reservoir M, and since those heights are determined by barometric pressure, the hydrostatic pressure also will change from time to time. However, it will be recognized that the ambient and hydrostatic pressures will vary inversely, because a high ambient pressure will force the fluid 25 down in reservoir I4, thus reducing the hydrostatic pressure. Conversely, a low ambient pres- F device, but mercury is preferred because of its density. To attain an absolute pressure of two atmospheres, with mercury in the regulating de vice, it is only necessary to place the lower end of bubbler tube 20 about thirty (30) inches below the level of the fluid in reservoir I4. If water was used as the fluid, the lower end of bubbler tube 20 would have to be immersed in about thirty-three (33) feet of water to provide absolute pressure of two atmospheres. The figures of two atmospheres is not the upper limit of pressures The ambient pressure 'eous hydrostatic pressure.

46 and burette 54.

attainable with this pressure regulating appathis regulatin apparatus. The exact total pressure will be determined by the sum of the instantaneous ambient pressure and the instantan- Insetting the regulating device to maintain a given pressure, the

"instantaneous ambient pressure is ascertained and is subtracted from the desired total or absolute pressure to indicate the required instantaneous hydrostatic pressure; and the bubbler tube 20 is extended down into the fluid 26 to provide that instantaneous hydrostatic pressure. The resilient sleeve 224 permits adjustment of the position of the bubbler tube ZO'relative to the reservoir 24 without any loss of pressure through leakage.

In Fig. -2 a pressure regulating device of the type shown in Fig. 1 is shown connected to a manometer of the U-tube type. The bubbler tube 2| of Fig. 2 is similar to the bubbler tube 20 of Fig. 1 except that it has a T-junction instead of an L at the top. That T-junction has an inlet22 and an outlet 28, which is connected tothe U-shaped manometer 32 by a flexible tube 30. The arms of the manometer contain a measuring fluid 36 of any desired density or quality; and a graduated scale 34 which is poeitioned between the arms of the manometer makes it easy to read the difference between the levels in the manometer. The left-hand arm of the inanometer is connected to a confined volume of gas at an unknown pressure by outlet 38; and the manometer will balance the known pressure in bubbler tube 21 against the unknown pressure on the'confined volume of gas. The diflference between the levels of the liquid in the arms of the manometer 32 will give a measure of the difference in pressure between the gas or air in bubbler tube 21 and the gas volume with which outlet 38 communicates. It will be noted that the gas or air introduced into inlet 22 does not pass into and through the manometer 32. Instead, that gas or air passes directly down bubbler tube 2| and out through spray trap it; the air, gas or vapor in manometer being dead or virtually static. This avoids loss of vapor from the fluid in the manometer.

Another use of the regulating device of the present invention is disclosed in 3, wherein the regulating device is connected to a gas measuring device. The outlet 28 of the bubbler tube 2! is connected to a leveling tube 45 by means of flexible tube at, L-shaped arm 52 and stopper 44. The leveling tube 48 can be moved up and down as desired; and when so moved the fluid M in that tube will seek its own level in the leveling tube The outlet of the leveling tube 46, which is denoted by the numeral ,8 is con nected to the inlet 52 of the burette 5-1 by a flexible tube 50.

In using this combination of devices, the levelingtube 45 is initially raised until the level of fluid in the burette 54 rises to the top of that burette' and fills the T-junction 5'1. Thereafter, the valve 55 is closed, the valve 58 opened, and the leveling tube is lowered until the fluid level in burette 54 reaches the desired graduation; thus showing that the desired volume of gas has been drawn into the burette 54. The fluid levels in tube 45 and burette M will be identical; the flexible tube 50 which permitted this movement of the leveling tube 56, also permitting the fluid to seek its own level. At this time, the pressure .on the gas in burette 54 will be precisely the same as the-known pressureyin lbubblertube 2!. Having thus obtained a quantity of gas whose volumehas been precisely determined ata known pressure, the operator opens valve 56 and raises the leveling tube 46 untilthe :level of the liquid in the burette 54 rises to the valve Stand expels the gas.

The valve 56 may be connected to a pot containing selenium, and thus the leveling tube Hi can force theinoculant in gaseous state into the pot to inoculate the selenium. By exerting the same pressure-on the gas in the system each time an inoculation is made, it is possible to attain exceedingly precise determinations of the amount of inoculant going into the selenium. Thus it is possible to make the inoculations exactly the same in each andevery instance, irrespective of changes in ambient pressure.

Another use of the pressure regulating device of the present invention is making precise distillations, distillation curves, and boiling point determinations, and that use is disclosed in Fig. 4. Th outlet 28 of the bubbler tube 2| is connected to a flask for condensed material. That flask is denoted by the numeral 66 and it is connected to the outlet 28 of bubbler tube 2| by flexible tube 6|], bent arm 62, and stopper 64. A drain tube 63 also extends through the stopper 64, and that tube is connected to a condenser 12 by means of a short flexible tube 10. The condenser 12 is connected to a side arm flask'lfi by means of a short flexible tube '74. A stopper 1-8 is provided in the top of the side arm flask l6, and that stopper supports a thermometer 80. With this arrangement, the material to be distilled, which is denoted by the numeral 82, will be heated, will rise upwardly, and will then be directed down- Wardly through the side arm of the flask 1'6 until it passes through the condenser '12 and is converted to the liquid form so it can draindown into the flask E6. The pressure exerted on the material in the flask 66 will always be constant since the pressure in the bubbler tube 2| will be constant. This facilitates precise distillation operations, and eliminates all variations due to ambient pressure variations.

By use of the regulating apparatus provided by the present invention it is possible to operate under any given pressure above ambient pressure and to maintain that pressure constant irrespec tive of the variations in ambient pressure. It is impossible to attain absolutely complete correction for the changes in ambient pressure, but the error is very small and is actually insignificant. Where th diameter of the reservoir M is one-tenth /10) of the diameter of the bulb III, the fluid level in bulb 10 will move only onehundredth as far as the fluid level will move in reservoir 14. Thus, there will be a. compensationfactor of ninety-nine percent (99%). An even greater compensation can be attained by further increasing the diameter of the-bulb l0 relative to the diameter of reservoir I4. The principal limitation to such increases in area is the added cost of mercury. Actually a 'correction of ninety-nine percent (99%) is satisfactory for all reasonable purposes. To minimize the amount of mercury required, the bulb II) can be made with a progressively flattened base so that the total volume of mercury involved is small compared to the area involved.

Whereas a preferred embodiment of the .present invention has .been shown and described in the drawing and accompanying description, it should be obvious to thoseskille'd in theartthat various changes may be made in the form of the invention without affecting the scope thereof.

What I claim is:

1. A device that is adapted to maintain gas under constant pressure irrespective of changes in ambient pressure and that comprises a container which has a closed end and an open end,

a liquid column within said container intermediate the ends thereof, an evacuated atmosphere between one end of said liquid column and said closed end of said container, the other end of said liquid column being exposed to ambient pressure through said open end of said container whereby said liquid column moves down whenever ambient pressure increases and moves up vwhenever ambient pressure decreases, and a bubbler tube, said bubbler tube extending down into said other end of said liquid column a predetermined distance to provide a desired hydrostatic .pressure, whereby gas passing through said bubbler tube will be under a pressure higher than the ambient pressure, said liquid column being movable in response to variations in ambient pressure to change the pressure required to pass gas through said bubbler tube and thus maintain the total instantaneous pressure in said bubbler tube constant.

2. A device that is adapted to maintain gas under constant pressure irrespective of changes in ambient pressure and that comprises a con- 'tainer which has a closed end and an open end, a liquid column within said container intermediate-the ends thereof, an evacuated atmosphere between one end of said liquid column and said closed end of said container, the other end of said liquid column being exposed to ambient pressure through said open end of said container whereby said liquid column moves in response to variations in atmospheric .pressure, and a pressure relief tube, said pressure relief tube extending down into said other end of said liquid column a predetermined distance to provide a desired hydrostatic pressure whereby gas passing through said pressure relief tube will be under a pressure higher than the ambient pressure.

3. A constant pressure device that comprises a container whichhas a closed end and an open end, a liquid column within said container intermediate the ends thereof, an evacuated atmosphere between one end of said liquid column and said closed end of said container, the other end of said liquid column being exposed to ambient pressure through said open end of said container whereby said liquid column moves in response to variations in ambient pressure, and a bubbler tube, saidbubbler tube extending down into said other end of said liquid column a predetermined distance to provide a desired hydrostatic pressure.

4. A constant pressure device that comprises a container which has a closed end and an open end, a liquid column within said container intermediate the ends thereof, an evacuated atmosphere between one end of said liquid column and said closed end of said container, the other end of said liquid column being exposed to ambient pressure through said open end of said container whereby said liquid column moves down Whenever atmospheric pressure increases and moves up whenever atmospheric pressure decreases, and a pressure relief tube, said pressure relief tube extending'down into said other end of said liquid column.

5. A device that comprises a container which has a closed end and an open end, a liquid column tube, said pressure relief tube extending down into said other end of said liquid column whereby gas passing through said pressure relief tube will be under a pressure higher than the ambient pressure.

6. A device that comprises an element which has an evacuated atmosphere therein and which has a portion thereof that is movable in response to variations in ambient pressure, and a pressure relief tube that is in juxtaposition to said pressure-responsive element and which has one end thereof closely adjacent said portion of said p-ressiue-responsive element, said one end of said pres-sure relief tube being disposed so it normally discharges to the atmosphere, said element responding to variations in ambient pressure to move said portion thereof toward and away from said one end of said pressure relief tube and thereby vary the effective size of said one end of said pressure relief tube and thus maintain the pressure said pressure relief tube constant.

'7. A device that is adapted to maintain gas under constant pressure irrespective of changes in ambient pressure and that comprises an element which has an evacuated atmosphere therein and which has a portion thereof that is movable in response to variations in atmospheric pressure, and a pressure relief tube that is in juxtaposition to said pressure-responsive element and which has one end thereof closely adjacent said portion of said. pressure-responsive element, said one end of said pressure relief tube being disposed so it normally discharges to the atmosphere, said element being movable in response to variations in atmospheric pressure to move said portion thereof toward and away from said one end of said pressure relief tube and thereby vary the eifective size of said one end of said pressure relief tube and thus change the pressure required to pass gas through, said pressure relief tube and thus maintain the total instantaneous pressure in said pressure relief tube constant, said pressure relief tube having a passageway for gas passing therethrough and having an arm that commvnicates with said pressure relief tube but is normally free of gas passing through said pressure relief tube, said arm containing virtually static gas under fixed pressure.

8. A constant pressure device that comprises a container which has a closed end and an open end, a barometric liquid column within said container intermediate the end-s thereof, an evacuated atmosphere between one end of said liquid column and said closed end of said container, the other end of said liquid column being exposed to ambient pressure through said open end of said container whereby said liquid column is movable in response to variations in ambient ,pressure, and a pressure relief tube that extends into said other end of said liquid column and discharges gas which passes through said liquid column to the atmosphere, whereby gas in said pressure relief tube will be under a pressure higher than ambient pressure.

9. A device that is adapted to maintain gas under constant pressure irrespective of changes in ambient pressure and that comprises a container which has a closed end and an open end, a liquid column of a barometer within said container intermediate the ends thereof, and a bubbler tube, said tube having one arm extending down into said liquid column and serving as a passageway for gas passing into said liquid column, said tube having another arm which is connected to said first arm but is normally free of gas passing to said liquid column, said second arm containing virtually static gas under fixed pressure.

10. A device that comprises a container which has a closed end and an open end, a liquid column of a barometer within said container intermediate the ends thereof, and a bubbler tube, said tube extending down into said liquid column, said liquid column being movable in response to variations in ambient pressure to change the pressure required to pass gas through said tube and thus maintain the total instantaneous pressure in said tube constant.

11. The method of maintaining a fixed pressure irrespective of changes in ambient pressure that comprises forcing gas down under the surface of a liquid column which moves upwardly and downwardly in response to ambient pressure.

12. The method of maintaining a fixed pressure irrespective of changes in ambient pressure that comprises forcing gas down under the surface of a liquid column which moves upwardly and downwardly in response'to ambient pressure, said column operating to move upwardly and increase the hydrostatic pressure when the ambient pressure decreases, thus keeping the instantaneous total pressure constant.

13. The method of maintaining a fixed pressure irrespective of changes in ambient pressure that comprises forcing gas down under the surfaces of a liquid column which moves upwardly and downwardly in response to ambient pressure, said liquid column moving upwardly with decreases in ambient pressure and moving downwardly with increases in ambient pressure.

14. The method of maintaining a constant pressure irrespective of changes in ambient pressure which comprises utilizing ambient pressure to vary the resistance to the passage of gas from a tube.

15. A device that comprises a column sealed at one end thereof, a reservoir connected to the other end of said column and open to the atmosphere, a liquid supported in said column and said reservoir by the difference between the ambient pressure and an evacuated atmosphere in said column above said liquid, and a bubbler tube that extends down into the liquid in said reservoir.

16. A device that comprises a sealed column, a reservoir connected to said sealed column, a fluid supported in said column and said reservoir by the difference between the ambient pressure and an evacuated atmosphere in said sealed column above said fluid, and a bubbler tube that extends down into said reservoir, and a seal between said bubbler tube and said reservoir that permits adjustment of the depth towhich said bubbler tube is moved.

17. A device that comprises a column sealed at one end thereof, a reservoir connected to the other end of said sealed column and open to the atmosphere, a liquid supported in said column and said reservoir by the difierence between the ambient pressure and an evacuated atmosphere in said column above said liquid, anda bubbler tube that extends down into the liquid in said reservoir, the diameter of said reservoir being smaller than the diameter of a portion of said column.

18. A device that comprises a column sealed at one end thereof, a reservoir connect-ed to the other end of said sealed column and open to the atmosphere, a liquid supported in said column and said reservoir by the difference between the ambient pressure and an evacuated atmosphere in said column above said liquid, and. a bubbler tube that extends down into the liquid in. said reservoir, the diameter of said reservoir being smaller than the diameter of a portion of said column, whereby the exposed are-a of the liquid in the reservoir is less than the exposed area of the liquid in the column.

19. A device that comprises a column sealed at one end thereof, a reservoir connected to the other end of said sealed column and open to the atmosphere, a liquid supported in said column and said reservoir by the difference between the ambient pressure and an evacuated atmosphere in said column above said liquid, and a bubbler tube that extends down into the liquid in said reservoir, said column having an enlarged diameter portion at the level of the liquid therein, said enlarged diameter portion being at least ten times the diameter of said reservoir.

20. A device that comprises a column sealed at one end thereof, a reservoir connected to the other end of said sealed column and open to the atmosphere, a liquid supported in said column and said reservoir by the difference between the ambient pressure and an evacuated atmosphere in said column above said liquid, and a bubbler tube that extends down into the liquid in said reservoir, the diameter of said reservoir being smaller than the diameter of a portion of said column, whereby changes in ambient pressure cause greater linear movement of the fluid in the reservoir than in the column.

DAVID W. RAU.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 766,820 Fulton Aug. 9, 1904 1,016,372 Smith Feb. 6, 1912 1,107,887 Bowser Aug. 18, 1914 1,205,434 Connell Nov. 21, 1916 1,371,866 Crompton Mar. 15, 1921 1,858,202 Watkins May 10, 1932 

